Candles have been around for thousands of years. First used fuels were animal fat or tallow and later bees wax, then came the paraffin and vegetable based wax, and now an even newer synthetic polymer type of fuel. For candle fuels to burn, capillary action is employed. A fibrous material or cotton wick draws the liquid fuel up to the flame. Candles have evolved over time, and many additions have been added, such as color, fragrance, oil and novelty objects. The reasons to burn candles other than just for providing light are vast in number. Popularity has increased usage and, according to the National Fire Protection Association (NFPA), candles contribute to a high incidence of fires, causing injuries and loss of life as well as property damage in the millions of dollars.
The Fire Analysis and Research Division of NFPA reports that home candle fires increased 15 percent from the year 2000 to 2001, and 34 percent of these fires have been shown to be caused by negligence due to unattended, abandoned or inadequately controlled candles. Forgetting to extinguish a burning candle is a problem important enough to be dealt with and seriously remedied. A flame needs fuel and oxygen to survive, and lack of either will extinguish the flame. The end stages of candle burning are the most critical. Typically, as a candle flame burns downward to the bottom of the candle, the fuel is depleted and the wick burns out. In a freestanding candle, where the structure itself is also its fuel, a problem arises when the remaining fuel bottom loses its structure and evolves into a hot molten pool. If not adequately placed on a non-combustible surface, the molten fuel can saturate and ignite the supporting structure, producing a fire. A candle in a container has a different problem due to the fact the fuel's heat is intensified. If the heat is high enough to substantially vaporize the fuel, an explosive phenomenon known as flashover can occur, whereby it no longer needs a wick to burn. Excessive heat alone can scorch the paint or labels off of metal containers and crack or break glass containers, spilling forth the remaining contents, presenting a fire hazard.
All-wax or freestanding candles are usually manufactured in molds with or without retracting center rods, for wicks to be placed after rod withdrawal. Another method of manufacturing is molding fluid fuel into long tubes. A ram device forces the hardening fuel wax out of the die. The rod is cut to length, then center-bored for receiving a wick. A sized wick is then placed in the wick hole and affixed at its bottom with sometimes only a label for holding. Wicks poured in place are still the larger manufacturing method. The difference between whether the wick is placed during or after molding is purely a manufacturing process and has no significant effect on how it burns. The fuel must be fluid when poured into the mold or extrusion tube. Paraffin fuel has a pour temperature of 130 to 150 degrees F. Gel polymer fuel materials have a pour temperature of 160 to 170 degrees F. Some candles are made without a wick anchor. That type of candle must always be placed on a non-combustible surface due to the physical make-up. A burning candle wick with an unsupported bottom can float freely and migrate to an outer wall of the candle when the candle is low. Migration to an outer wall causes burning through and spilling molten fuel and the lit wick, setting the stage for a fire. Wick clips are provided to anchor the bottom of the wick and are typically made of thin metal. They are center-punched and crimped to hold a wick in a vertical, upright position during the manufacturing process. The wick clip is usually attached to the candle by the wax fuel, but sometimes only a bottom label holds it in place. When the candle flame has pooled its remaining fuel at the candle's bottom, the molten fuel's heat releases the wick clip from a fixed position. The unrestricted burning wick and clip can move freely within the molten fuel. If the burning wick is adjacent to an outer wall, it becomes a fire hazard. The candle bottom which once had structure is reduced to a molten state, now presenting a potential for fire.
Container candles use the same or similar type of wick anchor or clip although some have a longer cylindrical hollow ferrule or neck that is center-formed during manufacture. This keeps the wick from tilting or falling over when the fuel becomes molten during its burn. Containers are made of many non-combustible materials, but metal or glass is usually employed. Thus, there is need for a way in which candle safety can be improved.